ASI will design, develop, prototype and evaluate an innovative strength training system that incorporates both computer and robotic technology, to provide vastly improved muscle rehabilitation thereapy capabilities which are not currently available in the marketplace. The initial design of the system is anticipated to be a two-jointed robotic arm mounted on a floor-fixed base. The robotic arm will be attached to a patient's extremity, allowing the patient to make both active and passive movements applicable to a variety of planned rehabilitative, therapeutic and/or strength training modes. The robot will be under the servo-control of a robotic computer capable of allowing specific patterns of movement and resistance to be employed. These specific movement and resistance patterns will allow various strength training procedures to be adapted for each patient's therapeutic need. Therefore, the robot can be programmed to provide passive movement for a patient attempting to regain range of motion in an affected limb. Both the passive and active resistance movement can be accomplished with assurances of safety for the patient and thus relieve the physical therapist from the therapeutic/rehabilitative exercise. The potential for such a device in the physical therapy, rehabilitation market is tremendous. The system proposed here would be a major advance in the physical therapeutic and other rehabilitative settings. It would be both an evaluation instrument as well as a systematic strength training system with more versatility and patient safety than has been available to date. The robotic components of the system would allow a therapist to set a basic exercise protocol for a patient, then be free to work with other patients, as the device would take over much of the therapist's time consuming activity of manipulation and monitoring.